A tri-fold card is typically employed for, e.g., a health insurance card (see, e.g., Patent Literature 1).
In a typical tri-fold card, e.g., a perforation line is formed for tri-folding at each folding line, or a piece of thick paper is used such that cutouts are formed to form mountain-folding lines.
However, folding portions of such a card are weaker than other portions. For this reason, there is a disadvantage that rupture is caused from the folding portions due to repeated use. On the other hand, when these folding portions are formed stronger, the thickness thereof increases, leading to a disadvantage that card handling is difficult.